Class: ActionDispatch::Journey::GTG::TransitionTable

Inherits:
Object
  • Object
show all
Includes:
NFA::Dot
Defined in:
lib/action_dispatch/journey/gtg/transition_table.rb

Overview

:nodoc:

Constant Summary collapse

DEFAULT_EXP = 
/[^.\/?]+/

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from NFA::Dot

#to_dot

Constructor Details

#initialize ⇒ TransitionTable

Returns a new instance of TransitionTable.



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# File 'lib/action_dispatch/journey/gtg/transition_table.rb', line 17

def initialize
  @stdparam_states = {}
  @regexp_states   = {}
  @string_states   = {}
  @accepting       = {}
  @memos           = Hash.new { |h, k| h[k] = [] }
end

Instance Attribute Details

#memos ⇒ Object (readonly)

Returns the value of attribute memos.



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# File 'lib/action_dispatch/journey/gtg/transition_table.rb', line 13

def memos
  @memos
end

Instance Method Details

#[]=(from, to, sym) ⇒ Object 



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# File 'lib/action_dispatch/journey/gtg/transition_table.rb', line 168

def []=(from, to, sym)
  case sym
  when String, Symbol
    to_mapping = @string_states[from] ||= {}
    # account for symbols in the constraints the same as strings
    to_mapping[sym.to_s] = to
  when Regexp
    if sym == DEFAULT_EXP
      @stdparam_states[from] = to
    else
      to_mapping = @regexp_states[from] ||= {}
      # we must match the whole string to a token boundary
      to_mapping[/\A#{sym}\Z/] = to
    end
  else
    raise ArgumentError, "unknown symbol: %s" % sym.class
  end
end

#accepting?(state) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/action_dispatch/journey/gtg/transition_table.rb', line 33

def accepting?(state)
  @accepting[state]
end

#accepting_states ⇒ Object 



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# File 'lib/action_dispatch/journey/gtg/transition_table.rb', line 29

def accepting_states
  @accepting.keys
end

#add_accepting(state) ⇒ Object 



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# File 'lib/action_dispatch/journey/gtg/transition_table.rb', line 25

def add_accepting(state)
  @accepting[state] = true
end

#add_memo(idx, memo) ⇒ Object 



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# File 'lib/action_dispatch/journey/gtg/transition_table.rb', line 37

def add_memo(idx, memo)
  @memos[idx] << memo
end

#as_json(options = nil) ⇒ Object 



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# File 'lib/action_dispatch/journey/gtg/transition_table.rb', line 103

def as_json(options = nil)
  simple_regexp = Hash.new { |h, k| h[k] = {} }

  @regexp_states.each do |from, hash|
    hash.each do |re, to|
      simple_regexp[from][re.source] = to
    end
  end

  {
    regexp_states:   simple_regexp.stringify_keys,
    string_states:   @string_states.stringify_keys,
    stdparam_states: @stdparam_states.stringify_keys,
    accepting:       @accepting.stringify_keys
  }
end

#eclosure(t) ⇒ Object 



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# File 'lib/action_dispatch/journey/gtg/transition_table.rb', line 45

def eclosure(t)
  Array(t)
end

#memo(idx) ⇒ Object 



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# File 'lib/action_dispatch/journey/gtg/transition_table.rb', line 41

def memo(idx)
  @memos[idx]
end

#move(t, full_string, token, start_index, token_matches_default) ⇒ Object 



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# File 'lib/action_dispatch/journey/gtg/transition_table.rb', line 49

def move(t, full_string, token, start_index, token_matches_default)
  return [] if t.empty?

  next_states = []

  transitions_count = t.size
  i = 0
  while i < transitions_count
    s = t[i]
    previous_start = t[i + 1]
    if previous_start.nil?
      # In the simple case of a "default" param regex do this fast-path and add all
      # next states.
      if token_matches_default && std_state = @stdparam_states[s]
        next_states << std_state << nil
      end

      # When we have a literal string, we can just pull the next state
      if states = @string_states[s]
        state = states[token]
        next_states << state << nil unless state.nil?
      end
    end

    # For regexes that aren't the "default" style, they may potentially not be
    # terminated by the first "token" [./?], so we need to continue to attempt to
    # match this regexp as well as any successful paths that continue out of it.
    # both paths could be valid.
    if states = @regexp_states[s]
      slice_start = if previous_start.nil?
        start_index
      else
        previous_start
      end

      slice_length = start_index + token.length - slice_start
      curr_slice = full_string.slice(slice_start, slice_length)

      states.each { |re, v|
        # if we match, we can try moving past this
        next_states << v << nil if !v.nil? && re.match?(curr_slice)
      }

      # and regardless, we must continue accepting tokens and retrying this regexp. we
      # need to remember where we started as well so we can take bigger slices.
      next_states << s << slice_start
    end

    i += 2
  end

  next_states
end

#states ⇒ Object 



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# File 'lib/action_dispatch/journey/gtg/transition_table.rb', line 187

def states
  ss = @string_states.keys + @string_states.values.flat_map(&:values)
  ps = @stdparam_states.keys + @stdparam_states.values
  rs = @regexp_states.keys + @regexp_states.values.flat_map(&:values)
  (ss + ps + rs).uniq
end

#to_svg ⇒ Object 



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# File 'lib/action_dispatch/journey/gtg/transition_table.rb', line 120

def to_svg
  svg = IO.popen("dot -Tsvg", "w+") { |f|
    f.write(to_dot)
    f.close_write
    f.readlines
  }
  3.times { svg.shift }
  svg.join.sub(/width="[^"]*"/, "").sub(/height="[^"]*"/, "")
end

#transitions ⇒ Object 



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# File 'lib/action_dispatch/journey/gtg/transition_table.rb', line 194

def transitions
  # double escaped because dot evaluates escapes
  default_exp_anchored = "\\\\A#{DEFAULT_EXP.source}\\\\Z"

  @string_states.flat_map { |from, hash|
    hash.map { |s, to| [from, s, to] }
  } + @stdparam_states.map { |from, to|
    [from, default_exp_anchored, to]
  } + @regexp_states.flat_map { |from, hash|
    hash.map { |r, to| [from, r.source.gsub("\\") { "\\\\" }, to] }
  }
end

#visualizer(paths, title = "FSM") ⇒ Object 



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# File 'lib/action_dispatch/journey/gtg/transition_table.rb', line 130

def visualizer(paths, title = "FSM")
  viz_dir   = File.join __dir__, "..", "visualizer"
  fsm_js    = File.read File.join(viz_dir, "fsm.js")
  fsm_css   = File.read File.join(viz_dir, "fsm.css")
  erb       = File.read File.join(viz_dir, "index.html.erb")
  states    = "function tt() { return #{to_json}; }"

  fun_routes = paths.sample(3).map do |ast|
    ast.filter_map { |n|
      case n
      when Nodes::Symbol
        case n.left
        when ":id" then rand(100).to_s
        when ":format" then %w{ xml json }.sample
        else
          "omg"
        end
      when Nodes::Terminal then n.symbol
      else
        nil
      end
    }.join
  end

  stylesheets = [fsm_css]
  svg         = to_svg
  javascripts = [states, fsm_js]

  fun_routes  = fun_routes
  stylesheets = stylesheets
  svg         = svg
  javascripts = javascripts

  require "erb"
  template = ERB.new erb
  template.result(binding)
end